5-amino-1-[2,6-dichloro-4-(trifluoromethyl)phenyl]-4-(ethylsulfinyl)-1H-pyrazole-3-carbonitrile

Phototransformation in soil

Link to relevant study record(s)

Reference

Endpoint:

phototransformation in soil

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

EPA Guideline Subdivision N 161-3 (Photodegradation Studies on Soil)

GLP compliance:

yes

Radiolabelling:

yes

Analytical method:

high-performance liquid chromatography

Details on sampling:

- Sampling intervals of soil samples: soil samples were taken after 0, 1, 3, 7, 14 and 32 days.
- Sampling method: soil samples were extracted (three times) wtih a mixture of acetonitrile and water (80 : 20 v/v). The volume of each extract was recorded and the three extracts taken from each sample were combined.

Details on soil:

COLLECTION AND STORAGE
- Geographic location: the soil was sampled on an agricultural field in Madera, California, USA.
- Sampling depth (cm): 15.2 cm (6 inches)
- Soil preparation: the soil was sieved (mesh size: 2 mm)

PROPERTIES
- Soil classification: sandy loam soil
- Soil texture
- % sand: 61
- % silt: 33
- % clay: 6
- pH: 7.8
- CEC (meq/100 g): 6.2
- Initial moisture at 1/3 atm (%): 9.8
- Water holding capacity: 9.8
- Bulk density (gm/cc): 1.38


PREPARATION OF SOIL
- Air dried / fresh: fresh
- Sterile / non-sterile: non-sterile

Light source:

Xenon lamp

Light spectrum: wavelength in nm:

> 280

Details on light source:

- Relative light intensity based on intensity of sunlight: 5175 W/m2 (equivalent to the maximum sunlight intensity on a hot summer day at latitude 50 °N)
- Duration of light/darkness: 12:12 h

Details on test conditions:

TEST SYSTEM
- Type, material and volume of test apparatus or thin layers: surface area of test vessel: 6.0 cm (length) x 3.5 cm (width) = 21.0 cm2
- Application procedure: surface application to 1 cm depth using a micro syringe
- Volume of test solution used/treatment: 134 µg
- Details of traps for volatile, if any: ethylene glycol trap and ethylene glycol-ethanol amine (2/1) traps

REPLICATION
- No. of replicates (dark): 12
- No. of replicates (irradiated): 12

MAINTENANCE OF TEST CONDITIONS SPECIFIED UNDER "DURATION"
- Temperature maintenance method: test vessels were placed in a mixture ethylene glycol: water (50 : 50) that was circulated continuously
- Moisture maintenance method: moisture was maintained at 75% of 1/3 bar

Duration:

21 d

% Moisture:

75

Temp.:

21 °C

Initial conc. measured:

0.6 kg/ha d.w.

Reference substance:

no

Dark controls:

yes

DT50:

34 d

Test condition:

artificial sunlight

DT50:

48 d

Test condition:

darkness

Transformation products:

yes

No.:

#1

No.:

#2

No.:

#3

No.:

#4

Details on results:

MAJOR TRANSFORMATION PRODUCTS (distinguish between dark and irradiated samples)
Sulfone accounted for 16% of the extracted activity in irridiated samples and for 19% of the extracted activity in the dark control.
Sulfonic acid accounted for 3% of the extracted activity in irridiated samples and the dark control respectively.

MINOR TRANSFORMATION PRODUCTS (distinguish between dark and irradiated samples)
Sulfide accounted for 2% of the extracted activity in irridiated samples and for 5% of the extracted activity in the dark control.
Amide acid accounted for 3% of the extracted activity in irridiated samples and the dark control respectively.

Validity criteria fulfilled:

not applicable

Description of key information

DT50 = 34 d in summer sunlight (50° North) (EPA Guideline Subdivision N, 161-3)

Key value for chemical safety assessment

Half-life in soil:

34 d

Additional information

The photodegradation of the substance in soil was investigated in a study conducted according to EPA Guideline Subdivision N 161-3. The substance was applied on a sandy loam soil and the soil samples irradiated for 32 days (12:12 h light/darkness). The results were compared with a second set of soil samples that was kept in permanent darkness. A half-life of 34 days in artificial sunlight and 48 days in permanent darkness was recorded for the test substance. The main degradation products were sulfone and sulfonic acid.